docs: Update installation guide

Author: ThomasVitale

README.md

@@ -28,15 +28,15 @@ Add the Kadras [package repository](https://github.com/kadras-io/kadras-packages
   ```shell
   kctrl package repository add -r kadras-packages \
     --url ghcr.io/kadras-io/kadras-packages \
-    -n kadras-packages --create-namespace
+    -n kadras-system --create-namespace
   ```
 
 <details><summary>Installation without package repository</summary>
 The recommended way of installing the Metrics Server package is via the Kadras <a href="https://github.com/kadras-io/kadras-packages">package repository</a>. If you prefer not using the repository, you can add the package definition directly using <a href="https://carvel.dev/kapp/docs/latest/install"><code>kapp</code></a> or <code>kubectl</code>.
 
   ```shell
-  kubectl create namespace kadras-packages
-  kapp deploy -a metrics-server-package -n kadras-packages -y \
+  kubectl create namespace kadras-system
+  kapp deploy -a metrics-server-package -n kadras-system -y \
     -f https://github.com/kadras-io/package-for-metrics-server/releases/latest/download/metadata.yml \
     -f https://github.com/kadras-io/package-for-metrics-server/releases/latest/download/package.yml
   ```
@@ -48,20 +48,20 @@ Install the Metrics Server package:
   kctrl package install -i metrics-server \
     -p metrics-server.packages.kadras.io \
     -v ${VERSION} \
-    -n kadras-packages
+    -n kadras-system
   ```
 
 > **Note**
 > You can find the `${VERSION}` value by retrieving the list of package versions available in the Kadras package repository installed on your cluster.
 > 
 >   ```shell
->   kctrl package available list -p metrics-server.packages.kadras.io -n kadras-packages
+>   kctrl package available list -p metrics-server.packages.kadras.io -n kadras-system
 >   ```
 
 Verify the installed packages and their status:
 
   ```shell
-  kctrl package installed list -n kadras-packages
+  kctrl package installed list -n kadras-system
   ```
 
 ## 📙&nbsp; Documentation
@@ -85,7 +85,7 @@ Reference the `values.yml` file from the `kctrl` command when installing or upgr
   kctrl package install -i metrics-server \
     -p metrics-server.packages.kadras.io \
     -v ${VERSION} \
-    -n kadras-packages \
+    -n kadras-system \
     --values-file values.yml
   ```